Process for extracting copper from its ores.



H. B. SLATER. PROCESS FOR EXTRACTWG COPPER FROM KTS ORES Patented J 11116 12, 1917.

APPLICATION FILED JULY 28. 1915.

Wye/War.- hemy Byron (Yb/ex.

' tracting copper V of ores containing action of the base HENRY BYIQON SLATER, OF LOS ANGELES, CALIEOBNIA.

YBOCESS FOB EXTRAGTING COPPER FROM ITS 03138.

Specification of Letters Patent.

Patented J une 12,1917.

Application filed July 28, 1915. Serial No. 42,348.

To all whom it may concern:

Be it known that I, I-lnnnYBYnoN SLATER, a citizen of the United States, residing at Los Angeles, in the county of Los Angeles and State of California, have invented a new and useful Process for Extracting (Jopper from its Ores, of which the following is aspecification.

This invention relates to a process of exfrom its ores by the action of a leaching solution containing ferric chlorid or like leaching agent, and the in vention is especially adapted for use with ores containing base metal compounds, such as calcium carbonate, which tend to precipitate the iron or other equivalent metal from the solution. An important ob]ect of the present invention is to provide for cyclic leaching, precipitating and regenerating operations in such manner that the requisite content ofiron or its equivalent may be provided in the leach, notwithstanding the depleting action due to the base metal compound in the ore.

My invention consists essentially in lea-ching the ore with a solution containing ferric chlorid, or its equivalent, together with suit- -cient sodium chlorid or equivalent chlorid to serve asa carrier for the cuprous chlorid formed in the leaching operation; precipitating the copper from the solution by means of iron, insuch manner as to restore to the solution the iron it has lost during the leaching operation; and then regenerating the solution in such manner to restore it to its original condition, or to a condition equivalent to its originalcondi- LlOIl, for repetition of the leaching operation, in cyclic manner.

In applying my process to the treatment ing operation reduces the ferric to ferrous chlorid, so that the 'irinmry loss of iron in the leaching operation is occasioned by the metal compound present. Under those conditions the accnmulatiml of iron in the precipitation of the copper by means oi iron tends to balance the loss of iron in leaching, andany lack of complete l balance may he made up as hereinafter set forth.

The accompanying drawing is a. diagrammatic elevation. partly in secti n, oi: an

' apparatus suitable for carrying out my invcntion.

a A bald apparnlns mnyi-omphsc an agitator native copper the leachor leaching tank 1, connected to receive the I leaching solution from a storage tank 2 through a valved pipe 3, and said'leaching tank having an outlet for the lixiviate through vahved pipe 4 to a lixiviate storage tank 5, which discharges through valved pipe 6 to the precipitating tank 7. From tank 7, a valved-pipe 8 leads to spent liquor tank 9, which is connected through valved outlet pipe 10 to the anode compartment 11, of a two compartment electrolytic cell, said cell having also a cathode compartment 12, separated' from'the anode compartment by a permeable diaphragm 14, consisting for example of asbestos cloth, and being provided with anode and cathode members and 16 in the respective compartments 11 and 12.

Said anode and cathode members maybe of any suitable 'material,

for example carhon.

Suitable means such as pump 17 with piping 18 and 19 is provided for returning 4 the. regenerated solution from the anode compartment of this cell to the storage tank 2. Another tank 20 is connected by valve pipe 21 with tank 5, so that a portion of the solution in tank 5 may bedrawn into said tank "ZOfor separate treatment, said tank 20 having a discharge pipe 22 leading. to the precipitator 7.

In. extracting copper from ore containing native copper and a base metal compound, such as calcite, my process may be carried out as follows: The leaching liquid, consisting of a solution of ferric chlorid in wa: ter, of a strength for example of onehalf to one per cent. ferric chlorid, and also containing sodium chlorid or its equivalent, 1n-v proportion of say live to fifteen per cent, and containing also, if desired, free chlorin and oxidation products thereof, for example, hypochlorous the storage tank 2,. The ore, crushcdxto a suitable state of division, is supplied to the leaching tank or agitator 1, and the leaching solution from tank 2 is supplied through pipe 2, to tank 1,so as to cover the ore, which is then agitated with such solution until the leaching operation is completed. leaching operation consists mainly in solution of the copper as chlorid, and particularly. as (-uprous chlorid, by the ferric chlorid, which is reduced at the same time to Ferrous chlorid. Any cuprous chlorid 'l'ormod in this oi-crntlon is retained in solution l reason oi the presence of sodium Phlox-id. At the same time any (rah-iron This acid, is supplied to carbonate present in the ore will react to some extent with the iron chlorid, especially in ferrous form, precipitating some oi'p the iron as carbonate or hydrate and causing some of the calcium to be taken up into the solution as chlorid; this nl0lid of calcium aids the sodium chlorid in retaining'the cu )rous chlorid in solution.

lhe lixiviate is discharged into tank 5, and thence into the precipitating tank T, where it is brought into contact with metal-- lic iron, which reduces to metallic state any copper contained in the solution, and also reduces any :t'erric chlorid in the solution to ferrous chlorid. In this operation the iron goes into solution as ferrous chlorid, and if there were no loss of iron in leaching this would cause an accumulation of the iron in the leaching solution. According to my invention, the base metal compound in the ore is utilized as a means of pIGClPltating the excess of iron, or so much of it as may be practicable, and I. prefer to carry out the process so that the solution. Nv'lilt'ill reaches the precipitating tank will be do plete d of iron to an amount eipiivaient to that which will be taken up in precipitating the copper present. It the action of the calcium carbonate in the ore is not sul'licient to produce such depletion, then a suitable agent may be added in the tank 5, be- .iore the solution is passed to the precipitating ta k, to take up or remove from actire condition a certain. amount of the chlorin present, so-that less iron will be taken up in the precipitating operation For this purpose 1 may use sodium hydroxid, formed in the regenerating stage of the process, such sodium hydroxid being added to the solution in tank or to a portion thereof, in sullicient amount; and at such temperatures as to react with the fer lric ehlorid present, to form sodiun'i clilorid and ferric hydrate. ll.- is prci'crrrd draii oii' a part of the solution from tankii, into tank QO'and to treatit with sodiunr hy droxid about 'lOO 1., so as to avoid precipitation of copper, the solutioubcing then passed along with the remainder of the solution from tank 5 into the precipitating tank T. in this manner the amount oi iron remaining in the leach as it pas-*zcsto the precipitating o1 1oration may be reduced and the amount of iron taken up in the precipitation may also be reduced so as to cn-' able the iron taken up in precipitation of the copper to balance the loss of iron in leaching. in case there is a tendency to overdepletiiin of iron in leaching, this may be corrected by increasing the amount of leaching solution for a given amount of ore.

'l roni the precipitating tank 7, the spent leach may be passed to storage tank 9', whence it is conducted through the anode compartment ll of the electrolytic cell. In

calcite present, is

ing the reduction of this excess of this compartment it is subjected to the action ol? free chlorin liberated at the anode 1;) by electrolysis of the sodium chlorid in the solution) and the leach is thereby regenerated, .Hlltll regeneration, consisting mainly in the conversion of the ferrous chlorill in the solution to ferric chlonid. The regenerative action may be continued after all of the ferrous ehlorid is converted to the .lerric state, so as to produce more or less-free chlorin, together with hypochlorous acid, such hypochlorous acid being i'ornua'l for example by the action of the free chloriu in theanode compartment on cathode products migratingthrough the permeable diaphragm from "the cathode compartmen11. The cathode compartment may contain a solution of sodium chlon'd in its equivalent, the electrolysis producing sodium hydroxid or equivalent hydroxid in the cathode compartment, and such hy droxid ditl'using more or less through the permeable diaphragm-into the anode com paitmcnt and ruictiug with the contents thereof to form hy iochlcrous acid.

'l.he regenerated solution is conducted or pumped from the anode compartment 11 back to the storage tank 2, ready for use in a repetition of the cycle on a fresh body or ore.

In case there is any copper oxid or carbonate presentin the ore, its solution will be attended with precipitation of iron from the ferric chlorid. In the case of the oxid, this reaction may be represented by the following equation:

SCnO ZFeGl, EH20 BGaCl, 2Fe(OH) In. this case, therefore, the accumulation ct iron in pweipitation of the copper balanced the precipitation of iron in the solution oi the copper, as far the copper is present in the form of oxid. This pro cipitation of iron by copper oxid or carnionaie present may reduce the a-n'iount of precipitatimi of iron by the base metal com pound (calcite) required for maintaining the iron balane' In case theprecipitation of iron by the action of the copper oxid or carbonate, tc'rther with that due to the in excessr the iron taken up in precipitation of thecopper, the ferric chlorid may be used in excess of the amount requireii for solution of the copper, so that an additional amount of iron will be taken up in the precipitation of thecopper, durerric chlorid to ferrous chlorid.

In the operation of the above described process, the reaction of the calcite or other base me val compound with the ferric ehlorid will, in gener. 1, result in theformation of a. soluble chlorid, for exampldin tho case of calcite present in the ore, calcium chlorid will be formed in the solution, and this chlorid will act as a carrier for cuprous chlorid interchangeably with sodium ehlorid. As the process proceeds in cyclic manner, the amount of calcium chlorid present in' the leach may progressively increase, and may, if desired, eventually supcrsede-the'sodium ehlorid. by reason of the gradual loss of the latter in washing, etc, and the gradual ac cumulation. of the calcium chlorid. If at any time it is desired to reduce the amount of calcium chlorid present, a suitablepre cipitant therefor may be added to the spent leacln-for example, sodium sulfate or sodium hydroxid taken from the cathode-compartment of the electrolytic cell, the excess of calcium being then precipitated as sulfate or as hydroxid, and sodium chlorid being formed in the solution in place thereof. A further advantage of this modelof operation is that the calcium chlorid present in the leach tends to inhibit the solution oi? the calcite or alkaline earth metal compound in the ore.

I have specified smliumohlorid as the agent used for retaining the cuprous chlorid in solution and as the source of the chlorin needed for regeneration. Any other suitable chiorid mayfhowever, be used inter chaugeably therewith, for example, the chlorid of any alkali, metal ehlorid or of any alkaline earth metal. And in particular, calcium 'chlorid may be used as such retaining agent, either by'gradual substitution thereotfor the sodium chlorid, in cyclic operation of the process, or by the use ofcalcium chlorid throughout the process instead of sodium chlorid.

What I claim is:

1. The process of extracting copper from gore's containing copper together with an alkal me earth metal compound capable oi? precipitating iron'from its solutions, which consists in leaching the ore with a solution.

containing ferric ehloi id, and or metallic c-hlorid servin to retain cuprousohlorid in solution where y the copper is dissolved and a portion of the iron is precipitated, removing the solution from the ore, )recipitating the. copper from the solution by theaction of metallic iron, in such manner as to, re-' store to the solution a quantity of'i'ron substantially equivalent to that lost in leaching, and then regenerating the solution by the action of freechlorin.

J 2. The process of extracting copper from ore containing native copper together with an alkaline earth metal compound capable of prcrhiitatiug iron from its solutions, which consists in leaching the ore with a solution containing ferric chlorid together with a metallic chlorid serving to retain cuprous chlorid in solution whereby the copper is dissolved and a portion of the iron is precipitated by the action of the base metal CUmpO'lllld, removing the solution from the ore, precipitating the copper from the solution by the action of metallic iron, in such manner as to restore to the solution a quantity of iron substantially equivalent to that lost in the leaching operation, and then regenerating the solution by the action of free chlorin.

3. The process of extracting copper from ore containing native copper together with tuli'itr, which. consists in leaching the ore with a solution of ferric ehlorid and calcium ing the solution from the ore, precipifitiipflthe copper from the solution by the som oi? metallic iron. in such manner as to restore to the solution a quantity of iron substuntiall y equivalent to that lost in the leaching operation, regenerating the solution by the action of free chlorin, and using theregenerated solution for leaching fresh ore, the calcium chlorid in the regenerated solution being utilized for retaining the cuprous copper in solution. i

4. The process of extracting copper from ores containing copper together with analeium compound, which consists in leaching the ore "with a solution of ferric chlorid and sodium chlorid, so as to dissolve the copper of the ore, and to cause precipi ation of a portion of the iron of the ferric chlorid and solution of a portion of the calciuniwf "tity of iron substantially equivalent to that lost in the leaching operation, and regenerating to produce a solution for repetition of the process, such solution containing calcium chlorid, serving as a carrier for cuprous chlorid in place of sodium ohlorid lost in the leaching operation In testimony whereof I have hereunto set my hand, at Los Angeles, California, this 21st day of July 1915.

/ IHENRY'BY-RON SLATER.

It is hereby uemified that in Letters Patent No. 1,230,078, granted Juno 12,

1917, upon the application of Henry Byron Slater, of Los Angeles, California, for

an im rovoment in Processes for Extractin Co or from Its Ores" an error p n poars in the printed specification requiring correction as follows: Page 2, lines I O Q-J 10, for the word "carmonat read carbonate; and that the said Letters Patent ohouid be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 7th day of August, 1)., 1917.

[SEALJ F. W. HECLAIY,

Acting Uommiuior-er of Patmltm 

